In a mesh network, a communication path can be configured via a desired route between a starting point node and an endpoint node. Accordingly, the mesh network can offer efficient operations.
To improve the reliability of the network, a protection channel is configured for a work channel. In this case, when a failure occurs on the work channel, data is transmitted via the protection channel.
However, a failure rarely occurs on a plurality of work channels at the same time in the mesh network. Therefore, Shared Mesh Protection is proposed as a method for efficiently configuring a protection channel in the mesh network. In Shared Mesh Protection, one protection channel is prepared for a plurality of work channels. Namely, one protection channel is shared by a plurality of work channels. A network where one protection channel is shared by N work channels is sometimes called 1:N protection. In contrast, a network where one protection channel is prepared for one work channel is sometimes called 1:1 protection.
A method for switching a communication path where a failure occurs to a bypass path in the mesh network is described, for example, in Japanese Laid-open Patent Publication No. 2003-258851. Other related techniques are described, for example, in Japanese Laid-open Patent Publication No. 2004-80434 and Japanese Laid-open Patent Publication No. 07-50656.
When a protection channel is shared, for example, by a work channel A and a work channel B, the protection channel may transmit data as a replacement for the work channel A or as a replacement for the work channel B. Accordingly, when one protection channel is prepared for a plurality of work channels, resources for the protection channel are reserved. However, the protection channel is not actually configured. When a failure occurs on any of the work channels, the protection channel is actually configured by using the reserved resources.
As described above, in the conventional Shared Mesh Protection, a protection channel is enabled due to an occurrence of a failure on a work channel. Here, to enable the protection channel, a configuration of hardware circuits is controlled in each node equipment on a path of the protection channel so that a data signal of a corresponding work channel is transmitted. However, a considerable amount of time is needed to control such a configuration of hardware circuits. Accordingly, the length of time needed from when a failure occurs on the work channel until a data transmission is recovered by using the protection channel is complete may be long. For example, when many nodes are provided between a starting point node and an end point node, the length of time needed to recover a data transmission is long.